Strain-induced anisotropy in fabric and hydraulic parameters of oil sand in triaxial compression

Dense locked Athabasca oil sand specimens were tested in drained triaxial compression with lubricated ends at confining pressures of 5-750 kPa. Computer tomography and scanning electron microscopy imaging techniques were used to examine the microstructural features (interlocked structure, grain fabric, and rearrangement inside and outside shear bands) of the intact and sheared specimens. The average hydraulic radii and tortuosity along three principal directions were also measured using thin section imaging and electrical resistivity measurement methods. It was found that changes in fabric and hydraulic parameters of oil sand in triaxial compression are highly inter-related. Intrinsic and induced anisotropies in permeability were observed.